A 0.2 g sample of pyrolusite is analyzed for manganese content as follows. Add 50.0 mL of 0.1 M solution of ferrous ammonium sulfate to reduce the MnO2 to Mn2 . After reduction is complete, the excess ferrous ion is titrated in acid solution with 0.02 M KMnO4, requiring 15.0 mL. Calculate the percent manganese in the sample as Mn3O4.

66.7%

Explanation:

The reaction for the titration of the excess ferrous ion is:

We calculate the moles of Fe⁺² from the used moles of KMnO₄:

Then we substract those 0.30 mmol from the original amount used:

The reaction between ferrous ammonium sulfate and MnO₂ is:

So we convert those 3.5 mmol Fe⁺² that were used in this reaction to MnO₂ moles:

Then we convert MnO₂ to Mn₃O₄, using the reaction:

Finally we convert Mn₃O₄ moles to grams:

And calculate the percent

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms